The Simple Network Management Protocol (SNMP) is a set of standards for monitoring and controlling components in a network, such as a telecommunications network or a computer network. Components managed through SNMP might include computers, routers, bridges, hubs, switches, mobile switching centers, base stations, gateways, and other network elements well known to one of skill in the art. Software applications within such network elements might also be monitored and controlled. As used herein, the terms “network resource” and “resource” will refer to any such hardware component, software application, or other object managed through SNMP.
Through the use of SNMP, network resources can be configured, network performance parameters can be monitored, and faults in a network can be detected. Resource configuration deals with specifying the values of the attributes of a resource. Performance parameters that are monitored might include availability, response time, accuracy, throughput, and utilization. Fault monitoring deals with detecting and reporting undesirable conditions in a network or a network resource.
An SNMP agent typically collects performance data and other information from one or more network resources. One or more SNMP agents then provide this information to an SNMP manager. In some cases, the SNMP manager requests information from an SNMP agent and the agent retrieves the requested information from a network resource and returns the information to the SNMP manager. The SNMP manager typically uses a Get command or a similar command to retrieve information in this manner.
In other cases, the SNMP agent might send information to the SNMP manager without a request from the SNMP manager. Unsolicited information might be sent from an SNMP agent to the SNMP manager at periodic intervals or when significant events, such as failures, occur in a network resource. A Trap command or a similar command is typically used to send data from an SNMP agent to an SNMP manager in this manner.
Upon receiving data from an SNMP agent, the SNMP manager might perform a statistical analysis on the data and display the results of the analysis on a user interface. Alternatively, the SNMP agent might conduct the analysis and send the results to the SNMP manager for the SNMP manager to display.
The SNMP manager can also be used to configure network resources. That is, the SNMP manager can send a desired value for an attribute of a network resource to the SNMP agent associated with that network resource. The SNMP agent can then set the attribute to the specified value. A Set command or a similar command is typically used to specify an attribute value in this manner.
Network resources and attributes of network resources are identified under SNMP through a model known as the Structure of Management Information (SMI). SMI specifies a tree-like hierarchical structure using a series of digits and dots to give a unique identifier to each network element, application, and attribute. The unique identifier is known as an Object Identifier or OID. As an example, a particular network element might be given an OID of 1.2.3. Applications running on that network element might then have OIDs of 1.2.3.1, 1.2.3.2, 1.2.3.3, etc. Attributes of application 1.2.3.1, for example, might have OIDs of 1.2.3.1.1, 1.2.3.1.2, 1.2.3.1.3, etc. (One of skill in the art will recognize that these OIDs have been simplified for the sake of clarity. Actual OIDs might have different hierarchical structures and would typically be considerably longer than these examples.)
To transmit or communicate regarding attribute information within an SNMP-managed network, the OID associated with the attribute and the value of the attribute are transferred between an SNMP manager and an SNMP agent. For example, if an SNMP manager wished to retrieve the value of attribute 1.2.3.1.3, the SNMP manager might issue a Get command with an argument of 1.2.3.1.3 to the SNMP agent associated with network element 1.2.3. The SNMP agent would then retrieve the value associated with that OID and return the value to the SNMP manager.
A mapping of network resources and attributes to their associated OIDs is contained in a data store known as a Management Information Base (MIB). The MIB might also contain descriptions for tables, attributes, and notifications, and other application data structure information. The MIB might take the form of a table where each row corresponds to a particular network resource and each column corresponds to an attribute of a network resource. The SNMP manager and the SNMP agent both have access to the application data structure information in the MIB so that they can communicate with one another using the appropriate OIDs.